Stabilization of fuel additives

ABSTRACT

THE PRESENT DISCLOSURE IS DIRECTED TO A METHOD OF STABILIZING FUEL ADDITIVES. THE METHOD GENERALLY ENTAILS INCORPORATING IN THE FUEL ADDITIVE AN EFFECTIVE AMOUNT OF GLYCEROL ESTER HAVING AT LEAST A   R1-CO-   GROUP, WHERE R1 REPRESENTS A HYDROXY SUBSTITUTED ALIPHATIC GROUP HAVING FROM ABOUT 11 TO ABOUT 24 CARBON ATOMS.

United States Patent 3,713,792 STABKLIZATIGN 0F FUEL ADDITEVES David ZR. Wiley, Warminster, Pm, assignor to Betz Laboratories, Inc, Trevose, Pa. No Drawing. Filed Dec. 23, 1970, der. No. 101,152 Int. Cl. C101 1/32, 9/00 US. Cl. 44-4 18 Claims ABSTRACT OF THE DISCLOSURE The present disclosure is directed to a method of stabilizing fuel additives. The method generally entails incorporating in the fuel additive an effective amount of glycerol ester having at least a group, where R represents a hydroxy substituted aliphatic group having from about 11 to about 24 carbon atoms.

BACKGROUND OF THE INVENTION The use of fuel additives for all fossil fuels, i.e., oil, coal, etc., has been widespread since the fuel additives function not only to enhance and promote combustion of the particular fuel but also to alleviate and in some instances to eliminate fireside and related problems.

The fuel additives that have proven to be most satisfactory are those which are composed of finely divided oilinsoluble metallic particles which are dispersed in an oil or oil-like medium. The additives are widely employed since they possess the capacity to reduce stack emissions, abate high temperature corrosion by the contaminants in fuels and in particular vanadium, to curtail low temperature corrosion attributable to the presence of sulfur in the oil, to reduce the deposition of slag on fireside surfaces, to reduce S0 emissions, etc.

The materials most frequently used as the metallic additives are the oil-insoluble forms such as iron oxide, magnesium oxide, magnesium hydroxide, magnesium sulfate, dolomite, kaolin, alumina, calcium oxide, and the like.

The attributes and some of the problems associated with these types of fuel additive products are documented in such patents as U.S. Pats. 2,845,338; 3,018,172; 3,036,- 901; 3,067,018 and 3,514,273.

As is emphasized in each of the above-referred to patents, although the products are quite successful in the particular applications, it is extremely difficult to formulate the additives so as to insure complete, uniform and stable dispersion of the metallic particles in the oil vehicle. Because the additives are in fact dispersions, it is a prerequisite to their successful use that the additive after perhaps months of storage remain as close in physical character to the additive as it was formulated. As with any dispersion, the propensity for the dispersed phase to settle is great. Accordingly, the settled product when applied to the fuel will, of course, not achieve the purpose desired since the settled particles will not be pumped, applied or incorporated in the fuel. The majority of the metallic ingredient or ingredients which are responsible for the effects of the fuel additive, will have deposited or settled and accordingly not be present in the necessary amount. Alternatively, the deposited or settled solids may plug pipes, thereby making pumping of the product difficult or impossible.

Accordingly, the fuel additive supplies are not only constantly seeking out new ingredients for the additives, but also constantly plagued with the problem of devising a system for insuring that the individual ingredients were homogeneously incorporated and dispersed in the oil vehicle and that the ingredients will remain dispersed for a ice reasonable amount of time, of course when the additive contains oil-insoluble ingredients.

Accordingly, the present inventor became quickly aware that the fuel additive problem was twofold and, therefore, directed his goals toward achieving a system which would not only permit the homogeneous and stable suspension or dispersion of the oil-insoluble ingredients, but a system which would permit the easy and simple application of the additive either through spray or pumping means.

It was also ascertained that the mere addition of surface active agents was not sufficient to provide the system and the goals desired.

The present invent-or discovered after consider-able investigation that if a minor but effective amount of at least one compound of the formula Hz H 1112 OR OR ha wherein R represents hydrogen, a lower alkyl and h) R10- where R is a hydroxy substituted aliphatic group having from about 11 to about 24 carbon atoms, with the proviso that at least one R is a 0 II R C group, that the fuel additive containing the oil-insoluble ingredients after proper mixing was stable and less prone to sludge formation and deposition. The compound may be incorporated in the fuel additive in an amount ranging from about 0.1 to about 4% by weight of the oil-insoluble constituents of the additives.

Compositions containing the oil-insoluble metallic par ticles may contain the particles on a weight basis in an amount of from about 10 to about 70% of the metallic particles such as the earlier mentioned iron oxide, magnesium oxide, magnesium hydroxide, magnesium sulfate, dolomite, kaolin, calcined and hydrated alumina, calcium oxide and the like.

Although any of the foregoing may be utilized as the oil-insoluble constituents, the most effective has proven to be a combination. This combination is composed of the oil-insoluble forms of magnesium and aluminum. For example magnesium and aluminum oxides and hydroxides have found extensive use. The satisfactory weight ratios of the magnesium to the aluminum are 1:1 and may range as high as 10:1. Conversely, in certain instances, it may be desirable to have an excess of aluminum over magnesium, for example, 10:1 aluminum to magnesium.

The particles of magnesium and aluminum range from about .1 to about 50 microns and preferably 0.5 to 15 microns in diameter. The oil vehicle (which is preferably present in an amount of from about 30% to by weight of the composition) in which the particles of the oil-insoluble metallic constituents are dispersed may be any oil ranging in choice from the vegetable oils such as those extracted either from vegetables or from seeds to the petroleum oils such as the mineral oils, i.e., paraffinic oils, naphthenic oils, halogenated products thereof, kerosene, mineral seal oils and similar petroleum fractions. The oils which are operable for this purpose are well known as evidenced by the patents referred to earlier. Basically oils having a viscosity of from about 30 to 1000 SUS F.) have been found to be acceptable.

The fuel additive also advantageously is formulated to contain a surface active agent.

Although with certain oil-insoluble metallic particle systems there may be certain restrictions as to the type surface active agent which can be used, i.e., the agent must be either anionic, cationic, or nonionic in nature, the present invention is not necessarily limited since anionic, cationic and nonionic are all operable.

4 tris (9,13-dihydroxy stearate); glycerate tris (10,12-dihydroxy stearate); glyceryl bis (12-hydroxy stearate); glyceryl mono (IZ-hydroxy stearate); etc. These compounds are prepared generally by reacting glycerol and a Suitable surfactants of the non-ionic and anionic types fatty acid having from 12 to 24 carbon atoms and prefsecondary fatty acid amines; quaternary ammonium compounds of the formula: RR N(CH Cl; Hodag C1000 which possesses a basic formula of etc.

The surface active materials (surfactants) may conveniently be incorporated in the additive in any amount ranging from about 0.7% to 6.5% by Weight. However, with the use of the present stabilizing compound, it is not an essential but only a preferable feature that the surfactant be included.

The feed rates 'of the fuel additives range in the case of fuel oils from about one pint to one gallon per 1000 erably 15 to 20 carbon atoms and having at least one double bond. The ester type product obtained is then epoxidized with a peracid such as peracetic acid and then subjected to gentle acid hydrolysis.

These compounds bear a close resemblance to various surface active agents such as the glycerol stearates, glycerol laurates, etc. The differences in chemical structures lies in the requirement that the present stabilizing compound contain hydroxyl functions in the long chain portion of its structure. Although not entirely clear, it is believed that this hydroxyl group is the highly functional group which effectuates the enhanced stability.

SPECIFIC EXAMPLES The fuel additives of the invention and those to which the inventive additives were compared were prepared generally by slowly mixing /2 the amount of oil of the formulation with all of the surface active agent, if used. The oil-insoluble metallic particles are then added to the oil over a short period of time and the resulting medium is mixed at a high blade speed to attain high shear forces for a short time, e.g., five minutes. Blade speed is reduced and the stabilizer is then added. After addition of the stabilizer, the blade speed is increased until uniform consistency is attained (e.g., 10 minutes) at which time the remaining portion of the oil was added and mixed at a low blade speed.

The fuel additives tested in the following table were prepared for comparative purposes with the following gallons of fuel oil. With respect to the feed range of the i di fuel additives when used in conjunction with coal, the feed rate ranges from about 0.16 to about 1 quart per ton of the coal.

The compounds which are within the scope of the where R is a hydroxy substituted aliphatic group having Rocket Oil B: A naphthenic oil having an SUS of 300 at 100 F.

Alkaterge C: An alkyl substituted oxazoline cationic surface active agent Magnesium oxide: MgO: Michigan Chemical No. 340

Aluminum oxide: A1 0 Reynolds RC-ZO-GF Stabilizer: G'lyceryl tris (l2-hydroxy stearate) Hodag C1000: Substituted cationic heterocyclic compound The table also sets forth the composition of the respective examples and the results of the indicated stability tests. The percentage indicated for each of the ingredients is on a weight basis.

TABLE I Composition of- Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9

Ingredients:

Stabilizer 0. 2 0. 5 0. 2 0. 5 0. 5 0. 5 0. 7 Alkaterge C 2.0 2. 0 2.0 3. 0 3. 0 3.0 2.0 2.0 Magnesium oxide 20.0 20. 0 20. 0 20. 0 20. 0 20. 0 20. 0 20. 0 20. 0 Aluminum oxide 22. 7 22. 7 22. 7 22. 7 22. 7 22. 7 22. 7 22. 7 22. 7 Rocket Oil B 55. 3 55. 1 54. 8 54. 3 54. l 53. 8 54. 8 54. 8 54. 6 Hodag C-lOO-O- 2. 0 Stability upon 3 days shaking at room temperature:

Sludge volume, percent 3 0. 5 3 1 Trace Trace Consistency Stability upon 15-day shelf storage:

sludge volume, percent 4 0. 5 Trace 2 Trace Trace Stability upon 35-day shelf storage:

sludge volume Trace Trace Trace 1 None.

2 Firm sediment.

from about 11 to about 24, and preferably 16 to 20' carbon atoms, with the proviso that at least one R is 0 R115- include glyceryl tris (l2-hydroxy stearate); glyceryl tris (9-hydroxy palmitate); glyceryl tris (IO-hydroxy palmitate); glyceryl tris (9-hydroxy stearate); glyceryl tris (IO-hydroxy stearate); glyceryl tris (9,12-dihydroxy stea- The data derived and recorded in Table l established conclusively that the inclusion of the stabilizer, i.e. glyceryl tris (12-hydroxy stearate) enhanced the stability of the formulations. This was borne out by a direct comparison of the sludge volume of the compositions of Examples 2 and 3 with Example 1 and Examples 5 and 6 with Example 4.

in addition the stability testing established that the compositions of Examples 7, 8 and "9 were quite stable rate); glyceryl tris (10,13-dihydroxy stearate); glyceryl after 35 days of shelf storage. This compared quite favorably with Examples 1 and 4 which after storage for only 14 days exhibited substantial sludge formation. In addition, the substitution of the Hodag surface active agent for the oxazoline surface active agent established that different surfactants were equally operable and effective when used in accordance with the present invention.

In order to establish the stability of a typical composition of the invention at slightly elevated temperatures and to establish the effectiveness of oils other than the Rocket Oil B, the composition of Example 3 was remade and subjected to the tests described hereafter. In addition, the composition of Example 3 was remade excepting that it (Example contained only 22.5% by Weight Roclret Oil B and 32.3% by weight of Eureka rs-4000 (a naphthenic oil having an SUS of 1000 at l'000 F.).

The results of the stability tests under the conditions recited were as follows:

The data derived and recorded in the foregoing Table 2 established that the inventive compositions were stable at elevated temperatures as well as room temperature and that the substitution of a different oil also produced a stable composition.

FIELD RESULTS In order to establish the effectiveness of the inventive compositions, field evaluations were conducted using a fuel additive produced as earlier described from on a weight basis, the following ingredients:

Percent Rocket Oil B 55.0 Alkaterge C 2.0 Glyceryl tris (12-hydnoxy stearate) 0.3 Aluminum oxide 22.7 Magnesium oxide 20.0

Plant A: This particular plant was using a packaged oil fired boiler to produce steam for a particular purpose. The plant was not using any fuel additives for its oil and was experiencing a two-fold problem:

(1) Between the first and second gas pass, heavy slag had built up requiring the removal of eighty tubes in order to clean the section; and

(2) There were extensive air heater problems due to deposition. More specifically, there was severe cold-end fouling and corrosion.

The fuel additive as described above was fed to the I fuel oil at a rate of 0.8 quart per 1000 gallons of oil.

Over the same period of time during which the plant had before experienced the slagging problem, cold-end fouling and corrosion, the treatment with the inventive composition completely minimized the problems encountered and permitted the furnace to remain on stream without shutdown. Moreover, the additive remained substantially stable over the period of time. The fuel additive was supplied and stored in bulk without significant sludge or deposition problems.

Plant B was using pulverized coal as its fuel. Prior to treatment with the inventive fuel additive, the plant was experiencing heavy slagging in the generating and superheater areas of the furnace and accordingly had to be shut down after short intervals for slag removal. Treatment of the coal with one pint per ton of the above described fuel additive not only solved the slag problem but also provided enhanced effectiveness due to better combustion of the coal. Moreover, for the period of the treatment of the coal, a period of months, no problems were encountered with respect to sludge or deposition in the additive.

Although the invention has been specifically illustrated with respect to certain metallic particles, surface active agents, oils and a particular stabilizer, substitution of other but equivalent materials will be operable for the purposes of the present invention.

Accordingly having described the invention, what is claimed is:

1. A fuel additive comprising a dispersion of finely divided oil-insoluble metallic particles in an oil containing a stabilizing amount of a compound having the general formula H2 H Ha t ()R 6R AR wherein R is hydrogen or o EAL where R represents a hydroxy substituted aliphatic group having from about 11 to about 24 carbon atoms, with the proviso that at least one R is and a surface active agent.

2. A fuel additive according to claim 1 wherein the compound is present in an amount from about 0.1 to 3% by weight of the oil-insoluble particles.

3. A fuel additive according to claim 1 wherein the composition comprises by weight from about 10% to about 70% oil-insoluble particles, from about 30% to about oil and from about 0.1% to about 4% by weight of the oil-insoluble particles of the compound.

4. A fuel additive according to claim 3 which contains from 0.7% to 6.5% of said surface active agent.

5. A fuel additive according to claim 3 wherein the oil-insoluble particles are a combination of magnesium and aluminum compounds and the weight ratio of magnesium to the aluminum is from about 10:1 to 1:4.

6. A fuel additive according to claim 5 wherein the combination is magnesium oxide and aluminum oxide and said weight ratio of magnesium to aluminum is from about 1:1 to about 10:1.

7. A fuel additive according to claim 5 which contains from about 0.7% to about 6.5% of said surface active agent.

8. A fuel additive according to claim 6 which contains from about 0.7% to about 6.5% of said surface active agent.

9. A fuel additive according to claim 7 wherein the oil is a petroleum oil.

10. A fuel additive according to claim 8 wherein the oil is a petroleum oil.

11. A fuel additive according to claim 1 wherein the stabilizing compound is glyceryl tris (l2-hydroxy stearate), the oil-insoluble particles are a combination of magnesium and aluminum oxides where the weight ratio of the magnesium to aluminum is within the range of from about 1:10 to about 10:1.

12. A fuel additive according to claim 11 wherein the compound is present in an amount of from about 0.1% to about 4% by weight of the particles, and the surface active agent is a cationic surface active agent.

13. A fuel additive according to claim 12 wherein the particles are present in an amount ranging from about 10% to about 70% and the oil is present in an amount of from about 30% to about 90%.

14. A method of preventing fuel oil or coal ash slag, low and high temperature corrosion and stack emissions in fuel oil or coal burning furnaces which comprises operating said furnace on a fuel oil or coal containing an effective amount of a fuel additive comprising a dispersion of finely divided oil-insoluble metallic particles in an oil containing a stabilizing amount of a compound having the general formula H2 H H2 (in (SR (m wherein R is hydrogen or where R represents a hydroxy substituted aliphatic group having from about 11 to about 24 carbon atoms, with the proviso that at least one R is additive in an amount of from about 10% to about and said oil is a petroleum oil and present in an amount of from about 30% to about 16. A method according to claim 15 wherein the compound is glyceryl tris (12-hydroxy stearate) and is present in an amount of from about 0.1% to 4% by weight of the particles.

17. A method according to claim 16 wherein the additive contains from about 0.7% to 6.5% of said surface active agent.

18. A method according to claim 17 wherein the agent is cationic.

References Cited UNITED STATES PATENTS 3,514,273 5/1970 Lee et al. 44-51 3,540,866 11/1970 Miller 4451 DANIEL E. WYMAN, Primary Examiner W. J. SHINE, Assistant Examiner US. Cl. X.R. 44-5 1 

